Piano-playing device



H. SANDELL PIANO PLAYING DEVICE Filed June 14, 1922 4 Sheets-Sheet 1727'2677557 fiZZ WE fiarmeli,

Oct. 19 1926.

H. K. SANDELL PIANO PLAYING DEVICE Filed June 14, 1922 4 Sheets-Sheet 3"mum Oct. 19 .1926.

H. K. SANDELL PIANO PLAYING DEVICE 4 Sheets-Sheet 4 Filed June 14. 1922.

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UNITED STATES 1,603,871 PATENT orries.

HENRY K. sANnELL, or GKICAGO, rumors, essrenon To 1vIILLs NOVELTY ooM-PANY, OF CHICAGO, ILLINOIS,

A CORPORATION OF ILLINOIS.

PIANO-PLAYHVG DEVICE.

' Application fi1ed June 14,

The present invention relates to improvements in piano playing devices,and more particularly to such devices operated by means of an electricalcurrent and controlled by perforated note sheets or bymanually operatedkeys, as desired. It will be fully understood from the followingdescription of an embodiment 'of' the invention, illustrated bytheaccompanying drawil'igs, wherein:

Figure 1 isan elevation of a piano playing device embodying the presentinvention, the central portion thereof being broken away;

Fig! 2 is an end elevation of the piano playing action illustrated inFig. 1, show ing in detail thev operation of a note-plays ing magnet andof the control magnets for the dampers;

Fig. 3 shows in detail a sectional View through the control magnets forthe control of the hamn'ier-rail;

Fig. 4 shows in plan the control magnets of Fig. 3;

Fig. 5 is a sectional View through the action on the line 5-5 of Fig. 1,showing in detail a note playing' action and the control magnets for theoperation of the hammer-rail;

Fig. 6 is a sectional view through a noteplaying magnet; and

Fig. 7 is a diagram'inatic view sliowing the circuits for the control ofthe various parts of the piano action both from a perforated note sheetand from manually operated keys and pedals. I

Referring more particularly to the drawings, the numeral 10 indicatesthe string plate of a piano, which may be, for example, of the characterdescribed and shown in my prior Patent No. 1.028.496 granted June i.1912. The strings are indicated' by numeral 11. The actions for theindividual keys are designed by numeral 12 and, as they do not form apart of the present invention, are not described in further detailherein. The action of each key is con trolled by a riser 13 actingagainst the jack butt 14 and actuated by an alternating currentnote-playing magnet 15, the construction of which will be furtherhereinafter described.

The length of stroke of the hammers is controlled lt y the position ofthe movable hammer-rail 16 carried by arms Ur manna 1922. Serial- No.5622226.

ed on pivots 16 which are supported on the bracket 16. A. spring 16tends to draw the han'im'er-rail towards the strings. At one end of thehammer-rail 16 a pin 17 pro ects, this pin being preferably covered witha felt roller 17 The pin 17 engagesone end of the hannner rail operatinglever 18, the other end of which is engagedby the felt-covered head 19of rod 20, operated by the movable core of control magnet 21. By theoperation of the control magnet 21, the rod 20 is operated either toforce the hammer-rail 16 back to its farthermost position to give a fullstroke to the hammers 22, or

is permitted to assume an intermediate position, correspondinglyreducing the stroke of the, hammers.

A second magnet 23 cooperates withthe magnet 21 and the rod 20 to holdthe rod in its extended position. eration of this co-operating magnetwill be clear from Figures 3 and 5; Figure 3 sl1o-W- ing the magnets andtheir co-operatin'g parts 'in detail.

liiagnet 21- is" formed as a coil or spool 24: of suitably insulatedwire, in the center of which is the movable core 25-. The coil 24 isformed on a cylinder of suitable nonmagnetic material 26. At one end ofthe coil a cylindrical member 27 projects into the opening through thecoil, the inner portion of this member being formed to provide a seatfor the end of the core 25. which may suitably be provided with a feltbushing 28 to deaden the sound of impact. A laminated iron frame 29 ofgenerally rectangular form completely surrounds the magnet undue heatingthereof being prevented by' its laminated construction. The

rod 20 is secured to the end of the core 25 and passes through asuitable bore in the member 27 and in the end of the frame 29, a feltbushing being provided-to" eliminate noise. At the end of the rod '20thehead 19 is mounted; being provided at. its end with felt pad 3-1, whichengages the hammer-rail operating lever 18. Back of the head 19' ismounted a felt washer 32 on the rod 20, the purpose of which will beclear from a consideration of the operation of the (to-operating controlmagnet 23.

Magnet 23 is mounted within' an iron frame 33'which is mounted to asuitabledepending supporting member 3% secured to the frame 29 of magnet24:; Within the The mode ofjjopcylinder 35. At its upper magnet 23 ismounted a cylinder of suitable non-magnetic material, for example,brass. A core or armature 36 is movably mounted within the cylinder 35.At its lower end the core 36 is provided with a projecting rod portion37 which passes through a felt bushing 38 in a suitable bore provided inthe cap 39 closing the lower end of the cylinder 35. A coil spring 40 inthe lower end. of the cylinder surrounds the rod-like projection 37 andbears against the end of the'core 36, tending to force it upwardly. Atits upper end the core 36 is provided with another rod-like projection41, which passes through a felt bushing 42 in the cylinder 35 and alsothrough a felt bushing 43 in the cap 44 closing the upper end of the endthe projection 41 is provided with a felt head 45, which normally bearsagainst the felt head 32 mounted upon the rod 20 operated by magnet 21.

The co-operation of the two magnets will be readily apparent from aconsiderat on of Figure 5. When the electromagnet 21 is momentarilyenergized by alternating current, the solenoid core 25 is forciblybrought to the center of the magnet and the rod 20 is actuated to pushthe end of the hammerrail operating lever 18. By this movement the feltpad 32- is brought to such a position as to entirely clear the felt head45 on the rod 41 operated by electromagnet 23, and the spring 40 in thelatter magnet, acting on the end of the core 36, forces the rod 41 andthe felt head 45 upwards against the rod 20 between the pad 32 and theframe 29. The elements are then in the position shown in Figure 5. Upondeene-rgizing the magnet 21, the head 45 then serves as a stoppreventing the return of the head 19 of rod 20, and thereby prevent thereturn of the hammer-rail operating lever 18 to its normal position. Amomentary closure of the circuit energizing the magnet 21 consequentlyresults in placing and holding the rod 20 in energized position, itsposition being maintained even after the magnet 21 has beendc-energized. With the parts in this position, energizing the magnet 23causes a retraction of the core 36 to the center of the magnet. Thisdraws the head 45 back to a position such as to clear the pad 32 on rod20 and permit the latter to return to its normal position with themagnet 21 de-energized. By means of this arrangement, for example, ifthe magnets are operated from a perforated music sheet, a singleperforation will permit closure of the circuit energizing the magnet 21and the parts operated by the magnet will be held in the position afterthe magnet is de-energized until a perforation permitting closure of thecircuit through magnet 23 energizes the latter. The'hammer-rail lever1.8 is then permitted to return to its normal position under the actionof its spring 16 Dampers 46 are lifted from the spring to produce thepedaling effect by the lever 47 which is operated by a pair ofco-operating magnets 21 and 23 of substantially the same type ofconstruction as electromagnets 21 and 23, and co-operating insubstantially the same manner. In these electromagnets, as shown inFigure 2, the various elements are indicated by the same numerals thatindicate corresponding elements in the electromagnets 21 and 23 inFigures 3 and 5, the suffix a being added to the several numerals. Itwill be apparent that a momentary energizing of the magnet 21? willoperate the lever 47 to lift the dampers 46, and the latter will beretained in the lifted position by co-operation of the magnet 23 untilthe latter is momentarily energized.

The cores of magnets 21 and 21 are preferably of laminated construction,as shown in Figure 4, undue heating thereof being prevented by thislaminated construction.

The construction of the individual noteplaying magnets 15 will be clearfrom a consideration of Figure 6. Each of these magnets is formed of aspool 48 of suitable insulated wire mounted in a metallic, preferablyiron frame 49. Within the. spool is a tube or hollow cylinder 50 ofnon-magnetic material, preferably brass. Slidably mounted within thistube is the magnetic core member 51, provided at its ends with rodlikeprojections 52 and 53. The rod-like projection 53 passes through abushing 54 in the cap 55 in the lower end of the tube 50 and serves as aguide for the movement of the core. The rod-like projection 52 passesthrough a similar bushing 56 in the cap 57 in the upper end of the tube50. The rod-like projection 52 is provided at its upper end with a head13 and acts a riser for operating the piano action, as shown in Figures2 and 5.

As willbe seen from Figures 1. 2 and 5. the note-playing magnets 15 arearranged in rows. each row of magnets heinfr mounted upon an angle bar5O extending transversely across and parallel to the string frame. Theangle bars 50 are insulatably mounted upon the supporting braces 51, theinsulation being indicated 52 A. channel bar 53* is insulatablysuspended from each angle bar 50 and is lined with insulating material.such as fiber, indicated at 54. A panel 55 of insulating material servesas a cover for this channel. bar, which is used as a conduit for theelectric cables controlling the individual notes. nals 56 are providedon the panels 55. to which are connected one of the terminal leads fromeach of the note-playing electromagnets, the control lines for thecorresponding notes being connected to the cor- Termipreviouslydescribed.

responding terminals inside the channel box or conduit 53. The oppositeterminals of the note-playing electromagnets are directly connected withthe angle bars which serve as a common connecting line for-all theelectromagnets.

The operation of the various circuits controlling the mechanical devicesof the piano willbe clear from a consideration of Figure 7. In thisfigure the various parts are shown diagrammatically, the parts andelectromagnets corresponding to those hereinbeforc described beingindicated by thesame reference numerals. Two main connections and 61 areprovided for the supply of alternating current for the operation of theinstrument. The line 60 is directly con nected with the contact roller61, over which moves the perforated note sheet 62. Cooperating with thecontact roller 61 and the note'sheet 62 are a plurality of contactmembers 63 controlling the note magnets 15. Other contacts controllingthe expres sion devices and the volume of sound are provided, as will behereinafter described. From each contact 63 a connector 4 leads to apoint of connection 56", with which is connected a terminal line fromthe corresponding note-playing magnet 15. The other terminals of thenote-playing magnets are all connected to a common connector or line 50,corresponding to the angle bar 5O The line 50 is connected with a coil66 which, in turn, is connected through line 67 with the other cur rentsupply line 61. The switch 84 is opened in playing by means of aperforation in the note-sheet. It will thus be apparent that when aperforation in sheet 62 corresponding to a given note passes between acontact 63 and contact roll 61, current will pass through that contactto the corresponding note-playing magnet 15, the connector 50", theinductance 66 and the line 67 to the outlet line 61. The fixedinductance of the coil 66 will determine the force with which the coreof the note-playing magnet is centered and consequently will determinethe volume of sound of the note.

For varying the loudness of tone additional means closed by circuitsthrough the contact roller 61 are provided. For clecreasing the currentand for correspondingly decreasing thevolume of sound, a contact 68 isprovided, which, when it engages the contact roller 61, closes a shuntcircuit through the line 69 and the coil 70 to the line 67. The coil 70is wound in the same direction the coil 66 and closure of this circuitconsequently increases the inductance and decreases the current throughthe note-playing electromagnets through which fllICllltS are closed fromthecircult through Contact 68. For producing a greater volume of sound,a contact 71 is provided, which,

when itengages contact roll 61 through a perforation in the note sheetprovided for the purpose, closes a shunt circuit through the line 72 andthe coil 7 3 to the line 67. The

coil 73 is Wound in a reverse direction to the coil 66 and consequentlywhen current is passed through coil 7 3, the inductance is decreased andthe current actuating the electromagnets 15 energized while the currentthrough contact 71 is closed, is greater than 61. A single perforationin the note sheet,

causing a momentary energizing of the electromagnet 21 is sutlicient, ashas been previously explained, since by co-operation of the core ofelectromagnet 23, the core of magnet 21 is held in position until magnet23 is energized. l/Vhen contact 75 engages contact roll 61' through aperforation in the note sheet, a circuit is closed through line 79 andelectromagnet 23, which is energized to retract its core and release thecore of its electromagnet 21 in the manner previously described. Thedamper control magnets 21" and23? are controlled in similar manner fromcontacts 80 and 81, respectively. The line leading from contact 80 toelectromagnet 21 is indicated by numeral 83 and that leading fromcontact 81 to electromagnet 23 is indicated by numeral 82.

In Figure 7 circuits are diagrammatically shown for the control of thepiano playing devices from keys and pedals such as are in usein'ordinar'y pianos. lVhen it is desired to use the manual and footoperated controls instead of the note-playing keys, the switch 84 isclosed, thereby esta-blishinga connection between the line 50" and theline 67 shunting out the inductance 66. The noteoperating keys areindicated diagrammaticallyin end elevation at 85. 'The base ot each keyis connected by a line 86 with the terminal 56" of: the correspondingnote-playing magnet 15. Below each key are mounted two coil springs, alonger spring 87 and a shorter spring 88. The springs 87 and 88 serve ascontact members, the spring 87 being engaged by the base of the ltey ona. slight depression of'the latter and the spring 88 being engaged on amore forcible depression of the key. Each of the contact springs 87 'isdirectly connected with a common connector 90 leading to a coil orinductance 66 which is in turn connected through line 91 with thecontact roller 61 The inductance 66 plays the same role in modulatin thesound produced by the electromagnets being the 88 and the base of thehey is closed, it isthus apparent that the inductance 66 is shuntedaround with a corresponding increase in current through theelectromagnet 15 being energized and resulting increased volume ofsound.

To soften the tone during manual operation, the pedal 93 may beemployed. This pedal is connected to i c main conductor 61 by aconnection When the pedal is depressed, it engages a contact 95, closinga circuit through the line 96 and coil TO to the line 91. The coil beingWound in the same direction as the coil (56, increases the inductance inthe latter and thereby de creases the current passing to thenote-playingelectromagnet 15 being energized at the moment. The operation ot thepedal 93 and the coil '70 thus corresponds tothat ot the contact'68 andthe coil 70 in operation with the note sheet. a

The pedal'97 controls the ene'gizing ot the damper operating magnets 21?and Vith the switch 98 closed, the pedal is connected to the main line(31. Normally the end of the pedal 9? engages contact thereby closingthe circuit through the line '100, line 83 and electromagnet 28. Ondepressing p dal 97 circuit through the contact 99 is opened and circuitthrough the contact 101 is closed. Current then passes through theconnecting line 102 and line 82 to electroma gnet 21 energizing thelatter to raise the dampers 46 from the strings. Release of the pedal 97breaks the circuit through contact 101 and immediately makes the circuitthrough contact 99, thereby immediately energizing the electromagnct 23*and releasing the damper.

I claim:

1. In a piano action, in combination, hammer actuating mechanism, amagnet coil, a freely movable core within the coil normally out ofcentral position therein, ,mea .s for supplying alternating current tosaid magnet coil, thereby bringing said core to central position, meansoperated by the movement of the core to operate the hammer actuatingmechanism, a coil in the circuit in series with said magnet coil fordetermining the inductance in said circuit and means for varying theinductance of said second-mentioned coil to vary the current passingthrough said n'iagnet.

2. In a piano action, in combination, hammer actuating mechanism, amagnet coil, a freely movable core Within the coil nornally out ofcentral position therein, means for supplying alternating current tosaid i 7 1st coil, thereby bringing said core to central position, meansoperated by the movement of the core to operate the hammer mechanism, acoil in circuit in series with said magnet coil for determining theinductance in said circuit, a coil inductively coupled With saidsecond-mentioned coil and wound in the same direction and independentlycontrollable means for passing alternating current through thelastmentioned coil to increase the inductance in the former coil,

3. In a piano action, in combination, hammer actuating mechanism, amagnet coil, a freely movable core Within the coil normally out ofcentral position therein, means for supplying alternating current tosaid magcoil, thereby bringing said core to central position, meansoperated by the movei'uent of the core to operatethe hammeracuiechaniiim, a coil in the circuit in series said magnet coil fordetermining the n hi ance in said circuit, a coil inductively coupledwith said second mentioned coil and 'u'ouu d in the reverse direction,and indcpendentiy controllable means for passin at .irnating currentthrough the lastmentioned coil to oecrease the inductance in the tormercoil.

l. In a pianoaction, in combination, hammer actuating mechanism, amagnet. coil, a "freely movable core Within the coil normally out ofcentral position therein, means for supplying alternating current tosaid magnet 0 il, "hereby bringing said core to central position, meansoperated by the movement of the core to operate the hammer actuatingmechanism, a coil in circuit in series with said magnet coil tor detrmining the inductance in said circuit, coils inductively coupled withsaid first-mentioned coil, one

of said coils being Wound in the same direction and the other in thereverse direct1on, and independently controllable means for passingalternating current through the last-mentioned coils to vary theinductance in the'first-mentioned coil.

5. In combination with a piano action, hammer actuating mechanismtherefor comprising single electromagnet coils for each hammer of saidaction, a freely movable core in each of said coils, said cores beingnormally out of central position, a common connector for one ofthe'terminals of each of said electromagnet coils, a coilin series withsaid common connection, independent connectors for the other terminalsof each of said coils, and independently controllable means for closingthe circuits through said last-mentioned connectorsto supply alternatingcurrent to the electromagnet coils, to thereby bring their cores tocentral position, and means operated by the movement of the cores of themagnets to actuate the corresponding hammers of the piano action.

6. In combination with a piano action, hammer actuating mechanismtherefor comprising single electromagnet coils for each hammer of saidaction, a freely movable core in each of said coils, said cores beingnormally out of central position, a common connector for one of theterminals of each of said electromagnet coils, an inductance coil inseries with said common connector, separate connectors for the otherterminals of said coils, independently controllable means for closing acircuit through each of said separate connectors to supply alternatingcurrent thereto, to thereby bring the cores to central position, meansoperated by the movement of the cores of the magnets to actuate thecorresponding hammers of the piano action, and means for varying theinductance of the coil in series With the common connector to vary theforce of movement of the hammers.

7. In combination With a piano action, hammer actuating mechanismtherefor comprising single electromagnet coils for each hammer of saidaction, a freely movable core in each of said coils, said cores beingnormally out of central position, a common connector for one of theterminals of each of said electromagnet coils, an inductance coil inseries With said common connector, separate connectors for the otherterminals of said coils, independently controllable means for closing acircuit through each of said common connectors to supply alternatingcurrent thereto, to thereby bring the cores to central position, meansoperated by the movement of the cores of the magnets to actuate thecorresponding hammers of the piano action, an additional coilinductively coupled With the coil in series With the common connector,and means for passing alternating current through the last-mentionedcoil to vary the inductance in the circuit through the electromagnets.

8. In combination with a piano action, hammer actuating mechanismtherefor comprising single electromagnet coils for each hammer of saidaction, a freely movable core in each of said coils, said cores beingnormally out of central position, independently controllable means forsupplying alternating current to each of said electromagnet coils, tothereby bring the cores thereof to central position, means operated bythe movement of the cores of the magnets to actuate the correspondinghammers of the piano action and means for varying the inductance in thecircuit of said electromagnet coils to vary the strength of currentpassing therethro-ugh.

9. In a piano playing device, incombin'ation With a piano action,alternating current magnets for actuating the individual hammers of saidaction, and a circuit for the control of each of said magnets includinga manually operable key, contact means closed by partial movement ofsaid key for closing the circuit and contact means operable on furthermovement of said key for reducing the inductance in said circuit.

10. In a piano playing device, in combination With a piano action,alternating current magnets for actuating the individual hammers of saidaction, and a circuit for the control of each of said magnets includinga manually operable key, contact means closed by partial movement ofsaid key for closing the circuit and independently controllable meansfor increasing the inductance in said circuit.

11. In a piano playing device, in combinaQ tion with a piano action,electromagnet means for actuating the individual hammers of said action,and a circuit for the control of each of said magnets including amanually operable key, contact means closed by partial movement of saidkey for closing the circuit and contact means operable on furthermovement of said key for varying the current in said circuit.

HENRY K. SANDELL.

